In 2016 Mike Mearls of WotC tweeted: “5e lifetime PHB sales > 3, 3.5, 4 lifetime,” meaning that the 5th Edition Player’s Handbook had by then outsold each of the previous versions (not including AD&D 1 & 2, for which WotC did not have exact figures). Whether 5th Edition D&D’s rules are wonderful or terrible in relation to its forbears is a question outside the scope of this inquiry.
Please also note that this is not an examination of the subjective qualities of the game itself.
That said, I have wherever possible avoided anecdotal evidence in favor of hard numbers. Note that I’m not an industry insider, and I only had access to publicly-available information. I wanted to dig into this question a bit to satisfy my own curiosity. In the four and a half years since then 5th Edition has obviously put Dungeons & Dragons back at the top of tabletop roleplaying sales. It’s undoubtedly selling well, but how well? Wizards of the Coast (WotC) released the 5th Edition of Dungeons & Dragons on a rolling schedule in 2014, starting with the beginner boxed set in June and culminating with the the Dungeon Master’s Guide in December.
